Method and apparatus for mobility procedure in a wireless communication system

Abstract

A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), the UE receives, from a first cell, a first signaling indicative of one or more random access resources of a second cell. The UE receives, from the first cell, a second signaling indicative of switching a Special Cell (SpCell) of the UE to the second cell, wherein the second signaling comprises at least one of a Physical Downlink Control Channel (PDCCH) signaling or a Medium Access Control (MAC) Control Element (CE). The UE initiates a random access procedure on the second cell in response to receiving the second signaling, wherein the random access procedure is performed by the UE using the one or more random access resources.

The invention claimed is: 
     
       1. A method of a User Equipment (UE), the method comprising:
 receiving, from a first cell, a first signaling indicative of one or more random access resources of a second cell; 
 receiving, from the first cell, a second signaling indicative of switching a Special Cell (SpCell) of the UE to the second cell, wherein the second signaling comprises a Medium Access Control (MAC) Control Element (CE); and 
 in response to receiving the second signaling from the first cell:
 applying a Cell Radio Network Temporary Identifier (C-RNTI) for the second cell, wherein the C-RNTI, applied for the second cell to which the SpCell is indicated to be switched to, is indicated by the first signaling received from the first cell; and 
 initiating a random access procedure on the second cell, 
 wherein the random access procedure is performed by the UE using at least one of the one or more random access resources indicated in the first signaling received by the UE from the first cell. 
 
 
     
     
       2. The method of  claim 1 , comprising:
 resetting a MAC entity in response to receiving the second signaling. 
 
     
     
       3. The method of  claim 1 , wherein:
 the first signaling is indicative of at least one of a cell configuration of the second cell, a measurement configuration of the second cell, an identity associated with the second cell, an index associated with the second cell or a dedicated preamble for the UE to use on the second cell. 
 
     
     
       4. The method of  claim 1 , wherein:
 the second signaling is indicative of at least one of an identity associated with the second cell, an index associated with the second cell, a preamble index associated with the random access procedure or a reference signal index associated with the second cell. 
 
     
     
       5. The method of  claim 4 , wherein:
 the random access procedure is performed by the UE based on a reference signal associated with the reference signal index. 
 
     
     
       6. The method of  claim 1 , wherein:
 the one or more random access resources comprise at least one of a random access preamble, reference signal information or one or more Physical Random Access Channel (PRACH) occasions associated with the second cell. 
 
     
     
       7. The method of  claim 1 , comprising:
 considering the second cell to be the SpCell in response to receiving the second signaling or in response to completion of the random access procedure. 
 
     
     
       8. The method of  claim 1 , comprising:
 applying one or more configurations indicated by the first signaling in response to receiving the second signaling. 
 
     
     
       9. The method of  claim 1 , comprising:
 in response to receiving the first signaling, applying a Channel State Information (CSI) reporting configuration associated with the second cell. 
 
     
     
       10. The method of  claim 1 , comprising:
 in response to receiving the second signaling, generating a Radio Resource Control (RRC) message for transmission to the second cell. 
 
     
     
       11. The method of  claim 1 , comprising:
 not considering the second cell to be the SpCell based upon receiving a Physical Downlink Control Channel (PDCCH) order initiating a second random access procedure associated with the second cell. 
 
     
     
       12. The method of  claim 1 , wherein the second signaling does not comprise information received by the first cell from the second cell. 
     
     
       13. A User Equipment (UE), comprising:
 a control circuit; 
 a processor installed in the control circuit; and 
 a memory installed in the control circuit and operatively coupled to the processor, wherein the processor is configured to execute a program code stored in the memory to perform operations, the operations comprising:
 receiving, from a first cell, a first signaling indicative of one or more random access resources of a second cell; 
 receiving, from the first cell, a second signaling indicative of switching a Special Cell (SpCell) of the UE to the second cell, wherein the second signaling comprises a Medium Access Control (MAC) Control Element (CE); and 
 in response to receiving the second signaling from the first cell:
 applying a Cell Radio Network Temporary Identifier (C-RNTI) for the second cell, wherein the C-RNTI, applied for the second cell to which the SpCell is indicated to be switched to, is indicated by the first signaling received from the first cell; and 
 initiating a random access procedure on the second cell, 
 wherein the random access procedure is performed by the UE using at least one of the one or more random access resources indicated in the first signaling received by the UE from the first cell. 
 
 
 
     
     
       14. The UE of  claim 13 , comprising:
 resetting a MAC entity in response to receiving the second signaling. 
 
     
     
       15. The UE of  claim 13 , wherein:
 the first signaling is indicative of at least one of a cell configuration of the second cell, a measurement configuration of the second cell, an identity associated with the second cell, an index associated with the second cell or a dedicated preamble for the UE to use on the second cell. 
 
     
     
       16. The UE of  claim 13 , wherein:
 the second signaling is indicative of at least one of an identity associated with the second cell, an index associated with the second cell, a preamble index associated with the random access procedure or a reference signal index associated with the second cell. 
 
     
     
       17. The UE of  claim 16 , wherein:
 the random access procedure is performed by the UE based on a reference signal associated with the reference signal index. 
 
     
     
       18. The UE of  claim 13 , wherein:
 the one or more random access resources comprise at least one of a random access preamble, reference signal information or one or more Physical Random Access Channel (PRACH) occasions associated with the second cell. 
 
     
     
       19. The UE of  claim 13 , the operations comprising:
 in response to receiving the first signaling, applying a Channel State Information (CSI) reporting configuration associated with the second cell. 
 
     
     
       20. The UE of  claim 13 , the operations comprising:
 applying one or more configurations indicated by the first signaling in response to receiving the second signaling. 
 
     
     
       21. The UE of  claim 13 , the operations comprising:
 in response to receiving the second signaling, generating a Radio Resource Control (RRC) message for transmission to the second cell. 
 
     
     
       22. A non-transitory computer-readable medium comprising processor-executable instructions that when executed by a User Equipment (UE) cause performance of operations, the operations comprising:
 receiving, from a first cell, a first signaling indicative of one or more random access resources of a second cell; 
 receiving, from the first cell, a second signaling indicative of switching a Special Cell (SpCell) of the UE to the second cell, wherein the second signaling comprises a Medium Access Control (MAC) Control Element (CE); and 
 in response to receiving the second signaling from the first cell:
 applying a Cell Radio Network Temporary Identifier (C-RNTI) for the second cell, wherein the C-RNTI, applied for the second cell to which the SpCell is indicated to be switched to, is indicated by the first signaling received from the first cell; and 
 initiating a random access procedure on the second cell, 
 wherein the random access procedure is performed by the UE using at least one of the one or more random access resources indicated in the first signaling received by the UE from the first cell.